LM3279_15 Datasheet, PDF (1/37 Pages) Texas Instruments – LM3279 Buck-Boost Converter With MIPI® RFFE Interface for 3G And 4G RF Power Amplifiers

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LM3279
SNVS970C – MARCH 2013 – REVISED OCTOBER 2014
LM3279 Buck-Boost Converter With MIPI^® RFFE Interface
for 3G And 4G RF Power Amplifiers
1 Features
•1 MIPI^® RFFE Digital Control Interface
• High-Efficiency PFM and PWM Modes with
Internal Seamless Transition
• Operates from a Single Li-Ion Cell: 2.7 V to 5.5 V
• Adjustable Output Voltage:
– RFFE Digital Control: 0.4 V to 4.2 V
– Analog Control: 0.5 V to 4.2 V
• 1-A Maximum Load Capability for V_BATT ≥ 3.2 V,
V_OUT = 3.6 V
• 2.4-MHz (typ.) Switching Frequency
• Seamless Buck-Boost Mode Transition
• Fast Output Voltage Transition: 0.8 V to 4 V in 20
µs
• High-Efficiency: 95% typ. at V_BATT = 3.7 V,
V_OUT = 3.3 V, at 300 mA
• Input Overcurrent Limit
• Output Overvoltage Clamp
• Internal Compensation
2 Applications
• 3G/4G Smartphones
• RF PC Cards
• Tablets, eBooks Readers
• Battery-Powered RF Devices
Simplified Schematic
1.5 ÛH
VBATT: 2.7V to 5.5V
10 ÛF
SW1
SW2
PVIN
SVIN
VOUT
FB
EN
GPO0
GPO1
DGND
LM3279 VCON
SGND
VIO
SDATA
SCLK
PGND
RF Control
Bits
VOUT: 0.4V to 4.2V
10 ÛF
RF PA(s)
2 x 0.47 ÛF
(PA decoupling caps)
BB or
RFIC
3 Description
The LM3279 is a buck-boost DC/DC converter
designed to generate output voltages above or below
a given input voltage and is particularly suitable for
Power Amplifiers operating from single-cell Li-Ion
batteries in portable applications.
The LM3279 has four modes of operation: Pulse
Width Modulation (PWM), Pulse Frequency
Modulation (PFM), standby, and shutdown. During
normal conditions, the LM3279 operates in full
synchronous PWM mode at 2.4-MHz typical switching
frequency, providing seamless transitions between
buck and boost operating regimes. Energy-saving
PFM mode increases efficiencies and current savings
during low-power RF transmission modes. For high-
transmit power, the device operates in PWM buck or
boost mode, whereas the device can transition
between PWM and PFM modes during low-power
transmit. The LM3279 can be controlled either via an
included MIPI RFFE Digital Control Interface or by
using an analog control from an external MCU,
offering design flexibility.
The power converter topology enables minimum total
solution size by using one small footprint and case
size inductor and two surface mount capacitors.
The LM3279 is internally compensated for buck and
boost modes of operation thus providing an optimal
transient response.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (MAX)
LM3279
DSBGA (16)
2.529 mm x 2.146 mm
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
PWM Efficiency (V_OUT = 2.4 V)
100
90
80
70
60
PVIN = 2.7V
PVIN = 3.0V
50
PVIN = 3.6V
PVIN = 4.2V
40
0
100 200 300 400 500 600 700
OUTPUT LOAD (mA)
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.